@cvp The background color can be set without objc_util as well. By default it is transparent, but dp.background_color = "blue" works for example.

The text color can only be set with objc_util. However you should be aware that this is not a public API - the UIDatePicker documentation explicitly says "The appearance of UIDatePicker is not customizable."

In general, if a property is not accessible through a normal getter/setter method, it's probably private and unsupported. You can often use tricks like setValue:forKey: or private methods (starting with an underscore) to read and write such properties anyway, but that may stop working in future iOS versions.